Polymethine sensitizing dyes and photographic emulsions



Dec- 20, 1960 L. G. s. BRooKER ETAL 2,965,4861

POLYMETHINE SENSITIZING DYES AND PHOTOGRAPHIC EMULSIONS Filed June 2, 1958 Fig mm1/ml rm J )I I 300 400 500 600 70 0 4 D/CYANOMETHYLENE"2 METHYL 6* [(1,3,5' TRIMETHYL" Fi g3 Mmm r|| +Hfm lm HMH 1,3 o/ETHYL -5-{2- [(l-ETHYL -2 (IH) -NAPHrHo [/,2] THlAzo- LYL/DENE) PROPENYL] -6- METHYL -4H-PYRAN -4 YL/oENE} sARs/TuR/c Ac/D Leslie 6.8'. Brooker Frank G. We bster IN VENTORS ATTORNEYS United States Patent() l .,POLYNIE'IHINESENSITIZING DYES AND t .,JPHOTOGRAPHIC `EMULSIONS "i yLeslie G. SwBrooker and `Frank Glenn Webster, Rochester, N.Y., assignors to Eastman KodakCompany, Rochester, N.Y., a corporation of New Jersey --HFiIedJune 2, 1958, Ser. No. 739,121

13 Claims. (Cl. 96'-105) This invention relates to novel polymethine dyes, methods for making such dyes, and photographic silver halide emulsions sensitized by means of such polymethine dyes.

Polymethine idyes, including merocyanine` dyes, yhave t been previously described wherein the .molecule contains a variety of heterocyclic nuclei. We have nowifound a new class of polymethine dyes which contain a pyran ring as :apart of thelintracyclic chain. Many of these. dyes are/useful in increasing thesensitivity of photographic silver Vhalide emulsions.

It is, therefore, anobject of our invention to provide `a `new class of polymethine dyes containing'a pyran ring. Another object `is to t polymethine dyes; Still yanother object is to provide photographic silver halide emulsions `spectrally sensitized provide methods for making such with the new polymethine dyes of our invention.` Other Objects will become apparent from a `consideration of the following description and examples.

. t. Our new` polymethine. dyes are `frequently useful in sensitizingphotographic silver halide emulsions, and-the -elect of threeof` the dyes of ourinvention `in conventional photographic silver halide `emulsions is illustrated dia- D/V\D1 wherein R represents an alkyl group-or? alcohol radical (e.g., methyl, ethyl, n-propyl,.n-butyl,1isobutyl,-namyl, isoamyl, -methoxyethyl, -ethoxyethyl, allyl A(i.e.,-vinyl methyl), benzyl (phenylmethyl), -phe`nylethyl,carboxymethyl, etc. `(especially alkyl groupst=containing from l to 4 carbon atoms), Rn and R1 each represents a -hydrogen atom, a lower alkyl group (e.g., methyl, ethyl, etc.),v or an aryl group (e.g., phenyl, o, mor Ap-tolyl,A etcr.,respe cially a monocyclic aryl group of the benzene series), d and n each represents a positive integer of `from lto 2, D and D1 each represents a cyano group, or alternatively, D and D, together represent the non-metallic atomslnecessary to complete an indandione nucleus (e.g., 1,^3di ketohydrindene, etc.), or a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ringpsuch as a pyrazolinone nucleus (e.g.,V `3-methyl-1-phenyl2pyrazo lin-S-one, lphenyl-2pyrazolin5-one, 1-(2-benzothiazol y1)-3-methyl-Z-pyrazolin-S-one,` etc.), anisoXazolinone nucleus (e.g., 3phenyl-Z-isoXazolin-S-one, `3rnethyl2 isoxazolin-S-one, etc.), an oxndole nucleus (e.g., fl`alkyl 2,3-dihydro-2foxindoles, etc.), a 2,4,6-triketohexahydropyrimidine nucleusV (e.g., barbituric acid or 2,-thiobarbi- V2,965,486 Patented Dec. 20, 1960 rice 3 `tui-ic acid, as well as their 1-alkyl (e.g., l-methyl, l ethyl,

"-ethoxycarbonylphenyD, etc.), or l-aryl (e.g;,

rhodanines (e.g.,`

etc.) derivatives), a rhodanine nucleus (i.e., 2-thio2,4 thiazolidinedione nucleus), such as rhodanine, 3-alky1- j3-ethylrhodanine, 3-allylrhodanne, etc.), or 3-arylrhodanines (e.g., S-phenylrhodanine, etc.), etc., a 2thio2,4oxazolidnedione nucleus (i.e., a 2thio 2,4(3H,5H)oxazoledione nucleus) (e.g., 3-ethyl-2-thio- 2,4-oxazolidinedione, etc.), a thianaphthenone nucleus fonewnucleus) (e.g., t3-ethyl-2-thio-2,5-thiazolidinedione, 4etc.), al2,4thiazolidinedione nucleus (e.g., 2,4-thiazoli- `dinedione, 3-ethy12,4thiazolidinedione, 3-phenyl-2,4-thi azolidinedione, ..3-a-naphthyl-ZA-thiazolidinedione, etc.),

a-,thiazolidinone nucleus (e.g., 4-thiazolidinone, 3ethyl 4.thiazolidinone, 3-phenyl-4-thiazolidinone, 3-a-naphthyl- 4-thiazolidinone, etc.), a 4-thiazolinone nucleus (e.g., 2- ethylmercapto-S-thiazolin-4-one, 2 alkylphenylamino 5- t thiazo1in-4ones, 2-diphenylamino-5-thiazolin-4-one, etc.), a 2-imino-2-oxazolin-4-one (i.e., pseudohydantoin) nucleus, a 2,4-imidazolidinedione (hydantoin)rnuc1eus (e.g.,

L 2,4-imidazolidinedione, 3-ethyl-Z,4-imidazolidinedione, 3-

phenyl-2,4-imidazolidinedione, 3-a-naphthyl2,4 imidaz- 2,4.-imidazolidinedione, 1,3diethyl-2-thio 2,4- imidazolidinedione, 1-ethyl-3-phenyl-Z-thio2,4irnidazolidinedione, 1-ethyl-B-a-naphthyl-Z-thio-2,4imidazolidinedione, 1,3-diphenyl-2thio-2,4-imidazolidinedione, etc.), a 2imidaz olin-S-one nucleus (e.g., 2n-propylmercapto2imidazolin-S-one, etc.), etc. (especially a heterocyclic nucleus containing 5 `atoms in the heterocyclic ring, 3 of said `atoms being carbon atoms, l of said atoms being a nitro- .groupconsistmg of a-mtrogen atorn,-anuoxygen atom,

`igen atom and 1 ofsaid atoms beingselected from the and a sulfuratom), and Zrepresents `the non-metallic atoms necessary to complete a heterocyclic nucleus containing from 5 to 6 atoms in the heterocyclic ring, such as-those selected from the groupfconsisting of a thazole nucleus `(e.g., thiazole,. 4methylthiazole, 4-phenylthiazole, 5-methylthiazole, 5-phenylthiazole, 4,5-dimethylthiazole, 4,5-diphenylthiazo-le, 4-(2thienyl)thiazole, etc.), a benzothiazole nucleus (e.g;, benzothiazole, 4-chlorobenzothiazole,V 5-chlorobenzothiazo1e, -chlorobenzothiazole, 7-

f chlorobenzothiazole, 4-methylbenzothiazole, S-methylbenbenzoxzole nucleus (e.g., benzoxazole, S-chlorobenzoxazole, 5-methylbenzoxazole, 5-phenylbenzoxazole, 6- methylbenzoxazole, 5,6-dimethylbenzoxazole, 4,6-dimethylbenzoxazole, 5-methoxybenzoxazole, S-ethoxybenzoxazole, S-chlorobenzoxazole, 6-me'thoxybenzoxazole, 5-

`hydroxybenzoxazole, -hydroxybenzoxazole, etc.),

selenazole, tetrahydrobenzoselenazole, etc.), a naphthoselenazole nucleus (e.g., naphtho[l,2]selenazole, naphtho[2,1]selenazole, etc.), a thiazoline nucleus (e.g., thiazoline, 4-methylthiazoline, etc.), a 2-quinoline nucleus (e.g., quinoline, 3-methylquinoline, S-methylquinoline, 7- methylquinoline, 8-methylquinoline, 6-chloroquinoline, 8- chloroquinoline, -methoxyquinoline, -ethoxyquinoline, 6-hydroxyquinoline, S-hydroxyquinoline, etc.), a 4-quinoline nucleus (e.g., quinoline, -methoxyquinoline, 7- methylquinoline, S-methylquinoline, etc.), a l-isoquinoline nucleus (e.g., isoquinoline, 3,4-dihydroisoquinoline, etc.), a benzimidazole nucleus (e.g., l,3diethylbenzimid azole, l-ethyl-3-phenylbenzimidazole, etc.), a 3,3-dialkylindolenine nucleus (e.g., 3,3-dimethylindolenine, 3,3,5- trimethylindolenine, 3,3,7-trirnethylindolenine, etc.), a 2- pyridine nucleus (e.g., pyridine, S-methylpyridine, etc.), a 4-pyrdine nucleus (e.g., pyridine, etc.), etc.

The polymethine dyes represented by Formula I above can advantageously be prepared by condensing a compound selected from those represented by the following general formula:

(II) .-Z

wherein R, n and Z each have the values given above, X represents an acid radical, such as chloride, bromide, iodide, perchlorate, thiocyanate, benzenesulfonate, p-toluenesulfonate, methylsulfate, ethylsulfate, etc., and .I represents an electronegative group, such as:

(IIa) -S-R2 wherein R2 represents an alkyl group (e.g., methyl, ethyl, etc.) or an aryl group (e.g., phenyl, tolyl, etc.), or: (11b) CH=oH-1\|I-Ra wherein R3 represents an acyl group (e.g., acetyl, propionyl, butyryl, benzoyl, etc.), and R1 represents an aryl group (e.g., phenyl, tolyl, etc.), or:

wherein R0 and R2 each have the values given above, together with a compound selected from those represented by the following general formula:

(III) o CH I ,-Rx

l /G\ D D1 wherein R1, D and D1 each have the valuesV given above.

In general, the condensations of the compounds of Formula II with those of Formula III can be carried out using approximately equimolar amounts of these two reagents. Larger amounts of one or the other of these ingredients can be employed in order to accelerate the reaction, although when R1 of the intermediates of Formula III represents a methyl group, it has been found that use of an excess of the intermediates of Formula II frequently leads to continued reaction so that a new class of dyes represented by the following general formula is formed:y

wherein R, R0, d, n, D, D1 and Z each have the values given above, p and m each represents a positive integer of from l to 2, R represents an alkyl group, such as those illustrated above for R (R can be the same or dilferent from R), and Z1 has values such as those illustrated above for Z (Z1 can be the same or diiferent from Z). As can be seen by reference to Formula IV, the reaction of a second molecule of the intermediate of Formula Il with the methyl group of the dyes represented by Formula I need not be carried out under such conditions that the second molecule of the intermediates of Formula II is identical to the first molecule of the intermediates of Formula II reacted with the intermediates of Formula III, i.e., varied intermediates of Formula II can be used for the reaction with the dyes of Formula I. This latter reaction leads to the formation of unsymmetrical dyes.

We have also found that the intermediates of Formula III can be reacted with an aromatic aldehyde, such as p-dimethylaminobenzaldehyde, p-diethylaminobenzaldehyde, etc. to provide dyes represented by the following general formula:

wherein R1, D and D1 each have the values given above, and R5 and R6 each represents a lower alkyl group, such as methyl, ethyl, etc.

The condensations of the cyclammonium quaternary salts of Formula II with the intermediates represented by Formula III, or with the dyes of Formula I where R1 represents a methyl group, or with an aromatic aldehyde, can be accelerated by the addition of basic condensing Iagents to the reaction mixture. Typical basic condensing agents include the trialkylamines (e.g., triethylamine, trin-propylamine, triisopropylamine, tri-n-butylamine, etc.), N,Ndialkylanilines (e.g., N,N-dimethylaniline, N,Ndiethylaniline, etc.), N-alkylpiperidines (e.g., N-methylpiperidine, N-ethylpiperidine, etc.), etc. The condensations can be carried out in the presence of an inert diluent, such as the lower alcohols (e.g., ethanol, n-propanol, isopropanol, n-butanol, etc.), 1,4-dioxane, diethyl ether, benzene, pyridine, quinoline, etc. The afore-mentioned condensations involving the intermediates of Formula II can also be accelerated by the addition of heat to the reaction mixture. In general, temperatures varying from room temperatures (ca. 25 C.) to the reflux temperau ture of the reaction mixture can be employed.

The intermediates of Formula III above can advantaffgeously lbe prepared condensing a compound selected `from those represented by the` following general formula:

wherein R1 has the lvalues given above withzan intermediate represented by the following general formula:

with those of `Formula VII can advantageously bezcarried out .in the presence of a dehydrating agent, such :as -a `carboxylic anhydride (e.g., acetic anhydride, butyric anhydride, etc. (or some other suitable dehydrating agent). The condensations can also be acceleratedby `heating the reaction mixture. Temperatures `up .to and including the reflux temperature of the reaction mixture have been 'found quite useful for `the purposes of our invention.

The following examples will serve to illustrate `more fully the method of making the intermediates and dyes of our invention. The examples also illustrate the useful sensitizing `eiect exhibited by many of the `dyes of .our invention. i

The following examples will serve to illustrate more fully the manner of practicing our invention.

O CH i l CH3 A mixture of 24."8 g. (1 mol.) of 2,6-dimethyl-4H- pyran-4-one, 36.8 g. (l mol.) of 1,3-diethylbarbituric acid and 100 ml. of acetic anhydride was heated at the reiluxing temperature for 15 minutes. The reaction ln1`ix- `ture was chilled, the solid was collected on a flterand O CHS I C 0H5 i ether. The suspension was filtered and the intermediate was washed with ether. The yellow powder was obtained in a yield of 62% and it melted at 193-194 C.

Example 3.-4-dicyanomethylene-256-dmethyl-4H-pyran A mixture of '24.8 g. (1 mol.) of 2,6-dimethyl-4H pyran-4-one, 14.5 g. (1 mol. `plus 10% excess) of malononitr'ile and 100 ml. of acetic anhydride was heated at the refluxng temperature for 15 minutes. After chilling, the solid was collected on a filter, transferred to a beaker containing ethanol. After stirring, the suspension was filtered and `the intermediate was washed with ethanol. The pale brown plates were obtained in a yield of 55% and they melted at IS7-188 C.

O CH3 I 06H6 Example 5.-5 (2,6-dimethyl-4H-pyran 4-ylidene)1, 3-diethyl-Z-thiobarbituric acid O CH3 l l CH3 A umixture lof 24.8 g. (1 mol.) of 2,6-dmethyl-4H- `pyran-4-one, 40.0 g. (1 mol.) of 1,3-diethy1-2-thiobarbituric acid and m1. of acetic anhydride was heated at the reuxing temperature for 15 minutes. The reaction mixture was chilled, the solid was collected on a filter and transferred to a beaker containing methanol. After stirring, the suspension was filtered and the inter- `mediate was washed with methanol. The orange'needles lwere obtained in a yield of 62% and they melted at `1Y90191 C.

Example 7.-'4 (2,6 dimelhyl xH-pyranJl-ylldene)- 3-methyl-1-phnyI-Z-pyrazolin-S-one A mixture of 12.4 g. (1 mol.) of 2,6-dimethyl-4H- pyran-4-one, 17.4 g. (l mol.) of S-methyl-l-phenyl-Z- pyrazolin-S-one and 50 ml. of acetic anhydride was heated at the reliuxing temperature for 30 minutes. After chilling`, the solidvwas collected on a filter and transferred to a beaker containing ether. After stirring, the suspension was filtered and the intermediate was washed ,with ether. The orange needles were obtained in a yield of `26% `and they melted` at 21S-216 C.

A mixture of 0.86 g. (1 mol.) of 4-dicyanomethylene- 2,6-dimethyl-4H-pyran, 3.84 g. (l mol. plus 110% excess) of 3ethyl2 ethylmercaptobenzothiazolium ethosulfate, 2.1 g. (1 mol. plus 320% excess) of triethylamine and 25 ml. of pyridine was heated at the refluxing temperature for minutes. The reaction mixture was -stirred in water, chilled and the water was decanted. The residue was stirred in methanol until crystalline, filtered and the, solid `was Washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a ilter and Washed with methanol. After another such purification the yield of dye was 18%. The red crystals With a silverreflex had a M.P. of 299-300 C. Withfdecomp'osition aud they sensitized a'photographic gelatino-silver-bromoiodide emulsion to about `585 ma with a maximum sensitivity at about 525 my.

A mixture of 0.86 g. (1 mol.) of 4-dicyanomethy1ene- 2,6-dimethyl-4H-pyran, 4.'4 g. (1 mol. plus 110% excess) of 1ethyl-Z-ethylmercaptonaphtho[1,2lthiazoliumethosulfate, 2.1:'g. (1`mol. 'plus 320% .exces s);'of triethylamine and 25 ml. of ,pyridine was heated at the re'- tiuxing temperature forllO minutes. The reaction mix ture was stirred in methanol, and after chilling,.,the dye was collected on a filter and Washed with methanol. The dye was dissolved in hot pyridine, the'solution was filtered, methanol was added, and after chilling, the, dye was collected on a filter. and washed with methanol. After another such purification, the yield of dye Vwas 5%. The light red crystals had a M.P. 300 C. and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 575 my. with a maximum sensitivity at about 540 my..

gEt

A mixture of 1.72 g. (1 mol.) of 4-dicyanornethylene- 2,6-dimethyl-4H-pyran, 4.50 g. (l mol.) of 2-(2-acetanilidovinyl) 3 ethylbenzothiazolium iodide, 1.1 g. (1 mol. plus 10% excess) of triethylamine and 25 ml. of pyridine was heated at the reiiuxing temperature for l0 minutes. The cool reaction mixture was stirred with ether. The ether was decanted and the residue was stirred in 200 ml. of hot methanol. The hot suspension was filtered and the solid was washed Withmethanol. After another such treatment the dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purification, the yield of dye was 20%. The dark green needles had a M.P. of 270-'271 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 690 mit with maximum sensitivity at about 610 mil.

A mixture of 0.86 g. (l mol.) of 4-dicyanomethylene- 2,6-dimethyl-4H-pyran, 434g. (1 mol. plus 100% excess) of 2 (2 acetanilidovinyl)-3ethylbenzoxazolium iodide,

i y i v`2.1 g. (1 mol. plus 110% excess) of `trietliylairline and 25 m1. of pyridine was heated at the refluxing temperature for 10 minutes. The reaction mixture was stirred in methanol, after chilling the dye was collected on `a CH3 CH:

A mixture `oi? 0.86 g. (l mol.) of 4-dic`yanomethylene- 2,6-dimethyl-4H-pyran, 4.46 g. (1 mol. plus 100% excess) of 2-(2-acetanilidovinyl)-1,3,3-trimethylpseudoindolium iodide, 2.1 g. (1 mol. plus 110% excess)`of tri- `ethylamine and 25 m1. of pyridine was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred in cold water, and after chilling the solid was collected on a lter and washed with methanol. The residue was stirred in hot methanol, and after chilling the dye was collected on a iilter and washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added and after chilling, the dye was collected on a filter and washed with methanol. After another such purification, the yield of dye was 9%. 'Ihe green crystals with `a coppery reex had a M.P. of 272-273 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 665 ma with maximum sensitivity at about 580 ma.

VA mixture of 0.86 g. (1 mol.) of 4-dicyanometliylene- 2,6-dimethyl-4H-pyran, 4.44 g. (1 mol. plus 100% excess) of 2(2-acetanilidovinyl-1-ethylquinolinium iodide, "e5 drops of acetic anhydride, 2.1 g. (1 mol. plus 110% excess) of triethylamine and 25 m1. of pyridine was heated at the reiluxing temperature for minutes. The reaction mixture was stirred in methanol, and after chilling the solid was collected on a lter and Washed with methanol. The residue was stirred in ml. of hotmethanol, the hot suspension was filtered and the solid was washed with methanol. After another like treatment, the dye was dissolved in hot pyridine, the solution was iltered, methanol was added, and after chilling the dye was co1- lected on the filter and washed with methanol. After another suchpuriication, the yield of dye was 51%. The dark green crystals had a M.P. of 283-284 C. with de- `10 composition, and rthey sensitized aphtographc gelatinosilver-bromoiodide emulsion to about 715 infr with maximum sensitivity at about 670mg.

A mixture of 0.86 g. `(1 mol.) of 4-dicyanomethylene 2,6-dimethyl-4H-pyr`an, 1.49 g. (1 `mol. plus 100% excess) of pdimethylamihobenzaldehyde, 2 drops of piperidine and 25 ml. of pyridine was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred in water, and after chilling the solid was collected on a lter and washed with methanol. Alter two recrystallizations from methanol, the yield of dye was 13%. The scarlet crystals had a M.P. of 212-214e C. with decomposition, and they sensitized a photographic gelatinosilver-bromoiodide emulsion to -about 670m# with maximum sensitivity at about 560 mp..

A mixture of 1.15 g. (1 mol.)\of 4dicyanome`thylene2 methyl-6-phenyl4H-pyran, 2.63 g. (1 mol. plus 50%) of 1-ethyl-2-ethylmercaptobenzothiazolium ethosulfate, 0.6 g. (1 mol. plus 10% excess) of triethylamine and 15 ml. of pyridine was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred lin methanol, and after chilling the solid was collected on a lter and Washed with methanol. The dye 'was `dissolved in hot pyridine, the solution was iiltered, methanol was added, and after chilling the dye was collected on a iilter and Washed with methanol. After another such purification, the yield of dye was 30%. The felt of orange-red needles with a gold reilex had a M.P. 31f0 C., and they sensitized a photographic gelatina-silverbromoiodide emulsion to about 600 mp. with maximum sensitivity at about 540 ma.

A mixtureY of 1.15 g. (1 mol.) of 4-dicyanomethylenei2- methyl6phenyl4H-pyran, 2.25 g. 1 mol.) of 2-(2-acet- Aauilidovinyl)f3#ethylbenzothiazoliurn iodide, 0.6 yg. (l

yield of dye'was 33%. Th'e' felt of dark needles had a M.P. of 258--258I C. with decomposition, and they sensitized a photographic gelatine-silver-bromoiodide emulsion to about 710 ma with maximum sensitivity at about 530 my. and 630mg.

C=CH i CH3 011151111 Ill-02H5 A mixture of 1.45 g. (1 mol.) of 5-(2,6dimethyl-4H pyran-4-ylidene)-1,3diethylbarbituric acid, 5.24 g. (1 mol. plus 50% excess) of 3ethyl-2-ethylmercaptobenzothiazolium ethosulfate, 2.1 g. (1 mol. plus 320%) of triethylamine and 25 m1. of pyridine was heated at the refluxing temperature for 10 minutes. The reaction mixture was stirred in water and the water was decanted. The residue was stirred in hot methanol and the solid was collected on a lter and washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a lilter and washed with methanol. After another such purification, the yield of dye was 27%. The red crystals with a silver recx had a M.P. of 273-28l C. with decomposition, and they sensitized a photographic gelatinosilver-bromoiodide emulsion to about 620 ma, with maximum sensitivity at about 540 ma.

Igan. Ha

Cial-11T Ill-02H5 Il O A mixture of 1.45 g. (1 mol.) of 5-(2,6dimethyl-4H pyran-4-ylidene)-l,3diethy1barbituric acid, 4.81 g. (l mol. plus 110% excess) of 1-ethyI-Z-phenylmercaptoquinolinium p-toluenesulfonate, 2.1 g. (1 mol. plus 320% excess) of triethylamine and 25 ml. of pyridine was heated at the refluxing temperature for 10 minutes. The reaction mixture was stirred in water, the water was decanted and the residue was stirred in hot methanol. After chilling, the solid was collected on a lilter and washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purication, the yield of dye was 45%. The felt of dark green crystals had a MP. of 249-25 0 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 600 my. and had a maximum sensitivity at about v590 ma.

A mixture of 1.45 g. (l mol.) of 5-(2,6-dimethyl-4H pyran-4-ylidene)-1,3diethylbarbituric acid, 2.25 g. (1 mol.) of 2-(2-acetanilidovinyl)-S-ethylbenzothiazolium iodide, 0.6 g. (1 mol. plus 10% excess) of triethylamine and 25 m1. of pyridine was heated at the refluxing temperature for 10 minutes. The reaction mixture was stirred in methanol, and after chilling the solid was collected on a lter and washed with methanol. The residue was stirred in hot methanol, the hot suspension was ltered and the solid washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purification,v the yieldV of dye was 36%. The Ygreen crystals with a coppery reflex had a M.P. of 268-270 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 700 ma with a maximum sensitivity at about 625 ma.

A mixture of 1.45 g. (1 mol.) of 5-(2,6-dimethyl4H pyran-4-ylidene)-1,3diethylbarbituric acid, 4.34 g. (1 mol. plus excess) of 2-(2-acetanilidovinyl)-3-ethylbenzoxazolium iodide, 2.1 g. (l mol. plus 320% excess) of'triethylamine and 25 ml. of pyridine was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred in water, and after chilling the solid was collected on a iilter and Washed with water. The residue was stirred in hot methanol, the suspension was ltered hot and the dye was washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a lter and washed with methanol. After another such purification, the yield of dye was 15 The violet crystals had a M.P. of 26S-267 C. with decomposition, and they sensitized a photographic gelatino-silverbromoiodide emulsion to about 670 ma with maximum sensitivity at about 620 mp..

A mixture of 1.45 g. (1 mol.) of 5-(2,6dimethyl-4H pyran-4-ylidene)l,3diethylbarbituric acid, 4.46 g. (1 mol. plus 100% excess) of 2-(2-acetanilidovinyl)1,3,3 trimethylpseudo-indolium iodide, 2.1 g. (l mol. plus 320%) of triethylamine and 25 ml. of pyridine was heated at `thereuxing temperature for minutes. The reaction mixture was stirred in Water, and after chilling the solid was collected on a lter and washed with Water. The residue was stirred in hot methanol, the suspension was ltered hot and the dye was Washed with methanol. The

` dye was dissolved in hot pyridine, the solution was ltered,

methanol Was added and after chilling the dye was collected on a lter and Washed vvith methanol. After another such purication, the yield of dye was 9%. The shiny green `crystals had a M.P. of 244-245" C. with decomposition.

[1,2] thiazolylidene)propenyl]-6-methyl4H-pyran4- 40 ylidene}barbiturc acid CICH-CHICH-t l CH3 i 02H5 l /C\ O=C (6:0 C2H5-N\ /N-CiHs C |l O .pyran-4-ylidene)1,3diethylbarbituric acid, 5.44 g. (1 mol.

plus 100% excess) of 2-(2jacetanilidovinyl)-l-ethyl- .naphtho[1,2]thiazolium p-toluenesulfonate, 1.02 g. (1

mol. plus 100% excess) of acetic anhydride, 2.1 g. (1 60 mol. plus 320% excess) of triethylamine and ml. of pyridine Was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred in methanol, and after chilling the residue was collected on a filter and Washed with methanol. The solid was stirred in hot methanol, the suspension was ltered hot and the solid was washed with methanol. `The dye was dissolved in hot pyridine, the solution was ltered hot, methanol was added, and after chilling the dye was collected on a `iilter and Washed with methanol. After another such purication, the yield of dye was 36%. The copperygreen `crystals had a M.P. of 226-227c C. with decomposition, and they sensitized a photographic gelatinosilver-bromoiodide emulsion to about 720 mit with maximum sensitivity at about 650 mp.

CH: o on cn=cH--N\ l l CH3 mol. plus excess) of p-dimethylaminobenzaldehyde, 3 drops of pipeidine and 25 ml. of pyridinervvas heated at the refluxing temperature for 10 minutes.

0 A mixture of 1.76 g. (1 mol.) of 1,3-diethyl-5-(2- methyl--phenyl-4H-pyran-4-ylidene)barbitluric acid, 2.63 g. (1 mol. plus 50% excess) of S-ethyl-Z-ethylmercaptobenzothiazolium ethosulfate, 0.6 g. (1 mol. plus 10% excess) of triethylamine and l5 m1. of pyridine was heated at the retluxing temperature `for 10 minutes. The raction mixture was stirred in methanol, and after chilling the solid was collected on `a iilter and washed with methanol.

The dye was dissolved in hot pyridine, the solution was ltered, methanol was added, and after chilling the solid was collected on -a lilter and washed with methanol. After another such purication, the yield of the dye was 47%. The felt of orange-red needles had a M.P, of 184185 C. with decomposition, and they sensitized a a photographic gelatiuo-silver-bromoiodide: emulsion to about 580m# with maximum sensitivity at about 560 mp. Example 25.-1,3 diethyl 5 {2|(3ethyI-2(3H -benzothazolylidene)-propenyll 6 phenyl 4H pyran 4- yldeheffbarbtzlrc acid A mixture of 1.76 g. (l mol.) of 1,3-diethy1-5-(2- methyl--phenyl-4H-pyran-4-ylidene)barbituric acid, 2.25 g. (l mol.) of 2-(2-acetanilidovinyl)-3-ethylbenzothiazolium iodide, 0.6 g. (1 mol. plus 10% excess) of triethylamine and 15 ml. of pyridine was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred in methanol and after chilling the solid was collected on a lter and washed with methanol. 'Ihe dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a filter and Washed with methanol. After another such purification the yield of dye was 42% The felt of green crystals with a coppery refiex had a M P. of 291-292 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 710 ma with a maximum sensitivity at about 650 ma. Example 26.--1,3 dethyl-5-{2-[(3ethyl2 (3H) -benzothiazolyldene) methyl] 6 methyl 4H pyran 4- A mixture of 3.06 g. (l mol.) of 5-(2,6dimethyl4H pyran-4-ylidene)-1,3-diethyl-2-thiobarbituric acid, 5.24 g. (l mol. plus 50% excess) of 3-ethyl-2-ethylmercaptobenzothiazolium ethosulfate, 1.1. g. (1 mol. plus 10% excess) of triethylamine, 25 ml. of pyridine Was heated at the refiuxing temperature for 10 minutes. The reaction mixture was stirred in methanol, and after chilling the solid was collected on a filter and Washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a filter and Washed with methanol. After another such purification, the yield of dye was 33%. The felt of red needles had a M P. of 282-283" C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 610 mp.. with maximum sensitivity at about 570 ma.

A mixture of 3.06 g. (1 mol.) of 5-(2,6dimethyl-4H- pyran-4-ylidene)-1,3-diethyl-Z-thiobarbituric acid, 4.5 g. (1 mol.) of 2-(2-acetanilidovinyl)-B-ethylbenzothiazolium iodide, 1.1 g. (1 mol. plus 10% excess) of triethylamine, and 25 ml. of pyridine was heated at the refluxing temperature for 10 minutes. The reaction mixture was stirred in methanol, and after chilling the solid was collected on a filter and Washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered,

16 methanol was added, and after chilling the dye was collected on a iilter and washed with methanol. After another such purification, the yield of dye was 51%. The felt of green crystals had a M.P. of -197 C. with decomposition, and they sensitized `a photographic gelatino-silver-bromoiodide emulsion to about 730 ma With maximum sensitivity at about 670 ma. Example 28.-1,3 dethyl 5 {2 [(1 ethyl- 2(1H) naphtho[1,2] thiazolylidene) 2 methylpropenyl]- 6 methyl 4H pyran 4 ylidene} 2 thiobarbiturc acid A mixture of 1.53 g. (1 mol.) of 5-(2,6dimethyl-4H pyran-4-ylidene)-1,3-diethyl-Z-thiobarbituric acid, 2.7 g. (l mol. plus 25% excess) of l-ethyl-Z-ethylmercaptopropenylnaphtho[1,2]-thiazolium ethosulfate, 0.6 g. (1 mol. plus 10% excess) of triethylamine and 25 ml. of pyridine was heated at the refiuxing temperature for 10 minutes. The reaction mixture was stirred in methanol, and after chilling the solid was collected on a iilter and washed With methanol. The dye was dissolved in pyridine, the solution was filtered, methanol was added and the solid was collected on a filter and washed with methanol. in 250 ml. hot methanol, the hot suspension was iiltered and the solid was washed with methanol. After another such purification, the yield of dye was 4%. The dark crystals had a M.P. of 254255 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 740 my. and had a maximum sensitivity at about 700 mp..

tered, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purification, the yield of dye was 54%. The coppery crystals had a M.P. of 178-179 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 620 ma n@ had a maXimum sensitivity at about 540 ma.

After another like treatment, the solid was stirred A mixture of 1.33 g. (l mol.) of 4(2,6dimethyl-4H pyran- -ylidene)-3-phenyl-2-isoxazolin-5-one, 2.75 g. (1 mol.) of 2 (2 acetanilidovinyl) 3 ethylbenzothiazolium iodide, 0.6 g. (l mol. plus of triethylamine and ml. of pyridine was heated at the refluxing temperature for 10 minutes. The reaction mixture was stirred in methanol, and after chilling the solid was collected on a filter and washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and the dye was collected on a filter and washed with methanol. After another such purification, the yield of dye was 11%. The dark crystals with a shiny refiex had a M.P. of 275-276 C. with decomposition.

A mixture of 1.33 g. (1 mol.) of 4(2,6dimethyl-4H- pyran-4-ylidene)-3-phenyl-2isoxazolin-5-one, 2.23 g. (l mol.) of 1,3,3-trimethylpseudoindolium iodide, 0.6 g. (1 mol. plus 10% excess) of triethylamine, 25 ml. of pyridine was heated at the refiuxing temperature for l0 minutes. The reaction mixture was stirred in water, the residue was stirred in hot methanol, and after chilling the solid was collected on a filter and washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purification, the yield of dye was 4%. The dark green crystals had a M.P. of IS7-158 C. with decomposition, and they sensitized a photographic ge- 1atino-silverbromoiodide emulsion to about 670 mp and had a maximum sensitivity at about 620 mp.-

accuse mol. `plus 100% excess) of triethylamine and 25 ml. of pyridine was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred in water, and after chilling the solid was collected on a filter and washed with water. The solid was stirred in methanol and the dye was collected on a filter and washed with methanol. The dye was dissolved in hot pyridine, the solution was ltered, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purification. the yield of dye was 14%. The red crystals had a M.P. of 277-278 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 600 mit and had a maximum sensitivity of about 500 ma.

A mixture of 1.4 g. (1 mol.) of 4-(2,6dimethyl4H pyran- -ylidene)-3-methyl-1-phenyl-2-pyrazolin 5 one, 335g.` (1 mol. plus 50% excses) of 2-(2-acetanilidovinyl)-3-ethylbenzothiazolium iodide, 0.6 g. l mol. plus 10% excess) of triethylamine and 25 ml. of pyridine was heated at the refiuxing temperature for 10 minutes. The reaction mixture was'stirred in water, the water was decanted, the residuewas stirred in hot methanol, and after chilling the solid was collected on a filter and washed with methanol. The dye was dissolved in Shot pyridine, the solution was filtered, methanol was added, and after chilling the solid was collected on a filter and washed with methanol. After another such purification, the yield of dye was 2%. The dark crystals with a shiny reliex had a M.P. of S12-313 C. with decomposition, and they sensitized a photographic gelatino-silver-bromoiodide emulsion to about 620 mit and had a maximum sensitivity at about 600 m/t.

A mixture of 1.45 g. (1 mol.) of 5(2,6-dimethyl-4H pyran-4-ylidene)1,3diethylbarbituric acid, 4.50 g. (2 mol.) of 2-(2-acetanilidovinyl) 3 ethylbenzothiazoliurn iodide, 2.2 g. (2 mol. plus 120% excess) of triethylamine and 25 ml. of pyridine was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred in methanol, and after chilling the solid was collected onY a lter and washed with methanol. After-two recrystallization from pyridine, the yield olf dye was 16%. The felt of dark crystals had a M.P. .300 C.

acid

A mixture of 1.45 g. (l mol.) of -(26A dimethyl-4H- pyran-4-ylidene)l,3diethylbarbituric acid, 4.44 g. (2 mol.) of 2-(Z-acetanilidovinyl)-l-ethylquinolinium iodlde, 2.2 g. (2 mol. plus 120% excess) of triethylamlne, 1.02 g. (l mol.) of acetic anhydride and 25 m1. of pyridine was heated at the reliuxing temperature for minutes. The reaction mixture was stirred in methanol, the sol.d was collected on a filter and washed with methanol. The solid was stirred in hot methanol, the suspension was filtered hot and the solid that was collected on the filter was washed with methanol. The dye was dissolved in hot pyridine, the solution was filtered hot, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After two recr-ystiallizations from pyridine the yieldwof dye was 7%. The darly greenv crystals had a M.P. of 3,03-304- C. with decomposition, and they sensitized al photographic gelatina-sihrer-bromo-` iodide emulsion t0 about 770 me with. a1 senti: tif/ity at about 575 mi and 6,60-

(32H5-Nv C Il s A mixture of 1.53 g. (l mol.) of 5-(2,6dimethyl-4H pyran-4-ylidene)-l,3-diethyl-Z-thiobarbituric acid, 5.44 g. (2 mol.) of 2-(2-acetanildovinyl)-l-ethylnaphtho[1,2] thiazolium p-toluene-sulfonate, 1.1 g. (2 mcl. plus 10% excess) of triethylamine, 1.02 g. (2 mol.) of acetic anhydride and 25 ml. of pyridine was heated at the reuxing temperature for 10 minutes. The reaction mixture was stirred in methanol, and after chilling the solid was collected on a filterv and washed with methanol. The solid was stirred in hot pyridine, the suspension was filtered hot, and the solid that was collected on the ffter was Washed with methanol. The dye was dissolved in hot cresol, the. solution was filtered, methanol was added, and after chilling the dye was collected on a filter and washed with methanol. After another such purificat on, the yield of dye was 2%. The dark crystals` had a MJ?. of 298-299 C. with decomposftfon.

It has also been found that the intermediatesl represented by For'mula II above can be condensed with. 4,6

:patitas dimethyl-5-ethoxycarbonyl-2H-pyran-2-one to lgive dyes somewhat related to those represented by Formula I above. The condensation involves the Z-methyll group .of the pyran compound. For instance, replacement of the 20 Y Y pyran intermediate of Example 8 bya molecularly equivalent amount of 4,6dimethyl-5-ethoxycarbonyl2llpyran 2-one leads to the formation of a compound represented by the following formula:

Example 3,17..-3-ethy-2.-(3,5,5-lrmethyl-2-cyclohexen-I ylidane)-methylbenzothazolium iodide CH3 CH3 H2O CH:

CzHs I 2-[3-(1-carbethoxy 1 cyanomethylene)5,5fdimethyl 1-cyclohexenl-,yli methylene-3-ethylbenzothlazoline (1.32 g., 1 mol.) and water (5 ml.) were dissolved in 30% hydrobromic acid in acetic acid (2O ml.) and heated under reflux for four hours. The reaction mixture was then concentrated to dryness under reduced pressure on the steam bath. The residue was dissolved in methanol (15 ml.), filtered and the filtrate precipitated with ether. The solid was dissolved in boiling water (l5 ml.) and the product precipitated by the addition of sodium iodide (2 g.). After chilling, the crude product was filteredf ofi, stirred with acetone, filtered and dried. After re-y crystallization from water, the yield of pure product was, 0175 g, (53%) M P. 23,748 C. decomposition. The, melting point showed n o depression on mixing with an authentic sample prepared by the condensation of iso. phorone, and. Z-methylbenzothiazole ethiodide.

2.('3carbethoxy 3 cyano-Z-phenylallylidene)3-ethylbenzothiazoline (Kendall, Suggate, and Mayo, British Patent 704,840, published March 3, 1954) (2 g., l mol.), was dissolved in concentrated hydrochloric acid and heated under refiux for one hour. The reaction mixture was evaporated to dryness under reduced pressure on the steam bath and the residue extracted with boiling water (15 ml.). The aqueous solution was tered and the crude product precipitated from the filtrate by the addition of sodium iodide (5 g.). After chilling, the product was filtered off, stirred with aceone, chilled and filtered. After recrystallization from water, the y'eld was 1.10 g. (52%); M.P. l'89.90 C. with decomposition. A` mixture of this sample and an authentic sample pref paredE the direct condensation of acetophenone and 3-ethyl-2-methylbenzothiazolium iodide showed. no. de: pression of the melting point.

21 As shown in the above examples, many of the dyes of our invention are particularly useful in manufacturing photographic, silver halide emulsions, serving to alter the sensitivity thereof. Sensitization by means of our new dyes is, of course, directed primarily to the ordinarilyemployed, gelatine-silver-halide,V developing-out emulsions. The dyes are advantageously incorporated in the washed, finished emulsion and should, of course, be uniformly distributed throughout the emulsion. In the preparation of photographic emulsions containing our new dyes, it 'is only necessary to disperse the dyes in the emulsions. The methods of incorporating dyes`in emulsion are simple and well known to those skilled in the art of emulsion making. It isv convenienttoadd the dyesfrom solutions in appropriate solvents. The solvent must, of course, be compatible `withthe emulsion 'and substan` tially free from any deleterious effect on the light-sensitive materials. Pyridine has proven satisfactory as a solvent for the majority of ournew dyes.

'I'he concentration of our new dyes in the emulsion can vary widely, i.e., from about to about 200 mgs. per liter of flowable emulsion. The concentration of the dye will vary according to the type of light-sensitive material in the emulsion and according to the effects desired. The suitable and most economical concentration for any given emulsion will be apparent to those skilled in the art upon making the ordinary tests and observations customarily used in the art of emulsion making.

To prepare a gelatino-silver-halide emulsion sensitized with one of our new dyes, the following procedure is satisfaotory: A quantity of the dye is dissolved in pyridine or other suitable solvent and a volume of this solution (which may be diluted with methanol) containingfrom 5 to 200 mgs.` of dye is slowly added to` about 1000 cc. of agelatino-silver-halide emulsion, with stirring. Stirring is continued until the dye is uniformly distributed throughout the emulsion. With most .of our new dyes, to 20 mgs. of dye per liter of emulsion sufiices to produce the maximum sensitizing effect with the ordinary gelatino-silver-bromide (including bromoiodide) emulsions. With fine-grain emulsions, which include most of the ordinarily-employed gelatino-silver-ch'loride emulsions, somewhat larger concentrations of dye may be necessary to secure the optimum sensitizing effect.

The above statements are only illustrative and are not to be understood as limiting our invention in any sense, as it will be apparent that our new dyes can be incorporated by other methods in many of the photographic silver halide emulsions customarily employed in the art. For instance, the dyes can be incorporated by bathing a plate or film upon which an emulsion has been coated, in the solution of the dye, in an appropriate solvent. Bathing methods, however, are not to be preferred ordinarily.

Photographic silver halide emulsions which can advantageously be sensitized by means of the new dyes of our invention comprise the customarily-employed gelatino-silver-chloride, gelatino-silver-chloro bromide, gelatino-silverbromide, and gelatino-silver-bromiodide developing-out emulsions.

Photographic silver halide emulsions, such as those listed above, containing the sensitizing dyes of our invention can also contain such addenda as chemical sensitizers, e.g., sulfur sensitizers (c g., allyl thiocarbamide, thiourea, allylisothiocyanate, cystne, etc.), various gold compounds (e,g., potassium chloroaunate, auric trichloride, etc.) '(see U.S. patents, W. D. Baldsiefen, 2,540,085, granted `February 6, 1951; R. E. Damschroder, 2,597,856, granted lMay 27, 1952, and H. C. Yutzy et al. 2,597,915, granted May 27, 1952), various palladium compounds, such as palladium chloride (W. D. Baldsiefen, U.S. 2,540,086, `granted February 6, 1951), potassium chloropalladate (R. E. iStauffer et al., U.S. 2,598,079, 4granted May 27, '1952),- etc., or mixture of such sensitizers; antifoggants, such as ammonium chloroplatinate (A,P.H. Trivelli etal., U.S. 2,566,245, granted August 2,8, 1951), 'ammonium chloroplatinite (A.P.H. Trivelii et, al., U.S. 2,566,263,`

granted August 28, 1951), benzotriazole, nitrobenzimid azole, 5nitroindazole, benzidine, mercaptans, etc. (see Mees-The Theory of the Photographic Process, Mac` millan Pub., 1942, page 460), or mixtures thereof; hard? eners, such as formaldehyde (A. Miller, U.S. 1,763,533, granted June 10, 1930), chrome alum (U.S. 1,763,533), glyoxal (J. Brunken, U.S. 1,870,354, granted August 9, 1,932), dibromacroleiu (O. Block et al., British 406,750, accepted March 8, 1934), etc.; color couplers, such as those described in I. F. Salminen et al. U.S. Patent a spectrogram showing the `sensitivity of an ordinary gel-atino-silver-bromiodide emulsion containing one of our sensitizing dyes. In Figure' 1, the curve depicts the sensitivity of an ordinary gelatino-silver-bromiodide emulsion containing 4-dicyanomethylene-2- (3-ethyl-2 (3H -benzothiazolylidene)methyl] 6-methyl 4H pyran. The pre paration of this dye is illustrated in Example 8 above. In Figure 2, the curve depicts the sensitivity of an ordinary'gelatino-silver-bromiodide emulsion containing 4-dicyanomethylene 2 methyl 6 [(1,3,3 trimethyl- 2(3H)-indolylidene)propenyl]-4Hpyran. The preparation of this dye is illustrated in Example 122 above. In Figure 3, the curve represents the sensitivity of an ordinary gelatino-silver-bromiodide emulsion containing 1,3- diethvl 5- {2 [(1 ethyl 2(1H) naphtho[l,2]thiazo lylidene) propenyl] 6 methyl 4H pyran 4- ylidene}barbituric acid. The preparationof this dye is illustrated in Example 22 above.

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

What we claim as our invention and desire secured by Letters Patent of United States is:

1. A photographic silver halide emulsion sensitized with a po'yrnethine dye selected from those represented by the following general formula:

wherein R represents an alkyl group containing from 1 to 4 carbon atoms, R0 and R1 each represents a member selected from the group consisting of a hydrogen atom, an alkyl group containing from 1 to 2 carbon atoms and a monocyclic aryl group of the benzene series, n and d each represents a positive integer of from 1 to 2, D represents a member selected from the group consisting of a cyauo group and radicals which, together with and bonded to D1, represent the non-metallic atoms necessary to complete a nucleus selected from the group consisting of a pyrazollnone nucleus, an isoxazolinone nucleus, an oxindole nucleus, a 2,4,6triketohexahydropyrimidine nucleus, a rhodanine nucleus, a 2thio-2,4-oxazolidinedione nucleus, a thianaphthenone nucleus, a 2thio2,5thazol idinedione nucleus, a 2,4-thiazolidinedione nucleus, a thiazolidinone nucleus, a 4thiazolinone nucleus, a 2- imino2oxazolin4one nucleus, a 2,4-imidazolidinedione 'noemen' nucleus, a .2-thio2,4-imidazolidinedione nucleus, and a 2imidazolin5one nucleus, D1represents a cyano groupv when D represents a .cyano group, .and Z represents .the non-metallicatoms necessary to complete a heterocyclic nucleus `.selected Afrom the group consisting of a thiazole nucleus, a benzothiazole nucleus, .a naphthothiazole nuc'leus, a,thianaphtheno-7',6,4,5-thiazole nucleus, an'oxazole nucleus, a'benzoxazole nucleus, a naphthoxazole nucleus, a selenazole nucleus, a benzoselenazole nucleus, a naphthoselenazole nucleus, a thiazoline nucleus, a 2-quinoline nucleus, a 4-quinoline nucleus, .a 1isoquino line nucleus, afbenzimidazole nucleus, `a 3,3-'dialkylindolenine nucleus, a 2-pyridine nucleus vand a 4-pyridine nucleus. y

2. A ,photographicfsilverhalide emulsion, as defined in claim l, wherein the ysilverhalideissilver bromiodide.

3. A photographic silverhalide emulsion, as dened in claim 1, wherein the silver halide is silver chlorobrom-ide.

'4. A photographic silver halide emulsion sensitized with a polymethine dye selected from those represented by the 'following general formula:

@s \CN whereinR represents `an alkyl 'group containing yfrom .1 to. 4 oar-bon atoms,y R1 represents a member selectedirom thegroup consisting Aof a hydrogenatom, an alkylgroup containingv from 1 to 2 carbon atoms-and `a monocyclic aryl group 'of the benzene series,A d vrepresents al positve integer of from 1 4to "2 and Z represents the nonlmetalli'c atoms necessary to complete a benzothiazole nucleus.

5. A photographic silver halide emulsion sensitized with 4dicyanomethylene 2 i(3-ethy1-2(3H)benzothiazolylidene) -methyll -6-methyl-4H-pyran.

6. A photographic silver halide emulsion sensitized with a polymethine dye selected from those represented by the following general formula:

Il-/-C\ i \`Q/ wherein R'represents an alkyl group containing from 1 to 4 carbon atoms, R1 represents a member selected from the group consisting of a hydrogen atom, an alkyl group containing from 1 to 2 carbon atoms and a monocyclic aryl group of the benzene series, d represents a positive integer of from 1 to 2, Q represents the nonme'tallclatoms necessary to complete `a 2,4,6-triketohexahydropyr'imidine nucleus, 'and Z represents the non-metallic atoms necessary to complete a benzothiazole nucleus. y7.`-A"photographic silver halide emulsion .sensitized 'with -lg34diethyl-5-{2Li(34ethyl 2(3H) `benzothiazolylidene)`methyl l -6-4H-pyran-4-yl'ldene}barbituric acid.

*18.A photographic silver halide emulsion sensitized fwithf'a polymethine dye selected from those represented by the vfollowing -general'formulm ,Z` L`n-'1\'-`c=cH(-'CH=cH d-1 wherein Rrepresents an alkyl ,group containing fromV .1Y

aryl ,group of the benzene series, d represents a positive integer of from 1 to 2,` Q represents the non-metallic atoinsrnecessary "to complete a 2,4,6-triketohexahydro-' pyrimidinev nucleus, and rZ represents the non-metallic atoms necessary .toV complete abenzoxazol'e nucleus.

'9. A photographic silver halide emulsion sensitized` with Vl-diethyl 5 {2 [(3-ethyl-2(3H)-benzoxazolylidene) propenylil 6 -methyl 4H-.pyran4yl-idene}barbituric acid.

`10 A `photographic silver halide emulsion sensitized with the polymethinedye selected from those represented by `the following general 'formular' wherein R `represents V*an alkyl group containing from 1 to 4 `carbon atoms, R1 `represents a member selected from the group consisting of a hydrogen atom, an lalkyl group containing At`rom`1 to 2 carbon atoms and a monocyclic aryl group of `tllebenzene series, d represents a positive integer of from 1 to 2, Q represents the nonmetallic atoms necessary yto --complete an isoxazolinone nucleus, andZ represents the non-metallic atoms necessary vtofcornplete va 3,3-dialkylindoleine nucleus. l11. A'photogr'aphic silver halide emulsion sensitized" with` 4-{2Lmethy-l* l l,3,3trimethyl-2(3H) indolylidene) propcnyl] 4Hspyran-'4-ylidene}3-phenyl2isoxazolin5 one.

12. A photographic `silver halide emulsion sensitized with a polymethine dye selected from those represented by the :following general formula:

References Cited in the tile of this patent UNITED STATES 'PATENTS 2,170,805 Brooker Aug. 29, 1939 2,610,181 vHayes -nc- Sept- 9, 195.2 2,691,581 AKnott Oct. 12, 1954 2,773,869 Leavitt Dec. 11, `1956 'OTHER REFERENCES .Chemical Abstracts, 16,' 3101 (Abstract of vBritillfle'd.

Journal, 1922,I, 51445).

vvChernic'al Abstracts, ,19, 530 (Abstract ofTrocLRoy. "'SoQrLOlidOnV-QSR2311733, .19.24). v"Wizinger .et .al.: Hely.V Chim. .Acta., 139, 1217.422 *(1956). 

1. A PHOTOGRAPHIC SILVER HALIDE EMULSION SENSITIZED WITH A POLYMETHINE DYE SELECTED FROM THOSE REPRESENTED BY THE FOLLOWING GENERAL FORMULA: 